Anjani Karunaratne - Academia.edu (original) (raw)
Papers by Anjani Karunaratne
Ceylon Journal of Science, 2022
Sri Lankan Journal of Infectious Diseases, 2021
Postharvest Pathology of Fresh Horticultural Produce, 2019
Bacteria in Agrobiology: Crop Ecosystems, 2011
... interest in biological control of soilborne pathogens, with research into biological control ... more ... interest in biological control of soilborne pathogens, with research into biological control ... the two disciplines is not surprising considering the species mentioned as PGPR and as ... studies, under controlled conditions incorporating the complex inter-actions between host, pathogen ...
Ceylon Journal of Science, 2018
The Sri Lankan diet of which the staple is rice, has unacceptable levels of antinutritional subst... more The Sri Lankan diet of which the staple is rice, has unacceptable levels of antinutritional substances, particularly phytic acid, which is associated with fibre, a dietary component originating from plant sources of food. Low anthropometric indicators among preschool children suggestive of undernutrition have remained static over several years. Some microbes that ferment food are known to produce phytase that metabolize phytic acid in addition to providing other benefits. Some of these microbes in fermented foods serve as probiotics, which help maintain homeostasis within the gut microbiota, thus providing a wide range of health benefits. At present, it is a worldwide trend to incorporate probiotics to the daily diet in fermented foods, while a market for novel probiotic foods is catching on. In the gut, probiotics can thrive on indigestible carbohydrates (fibre) serving as prebiotics. Therefore, designing synbiotic foods having both probiotics and prebiotics with enhanced benefits is also becoming popular globally. This review evaluates the feasibility of introducing a wide range of fermented foods to the Sri Lankan diet. Such a move is envisaged to diversify the local diet thus helping to alleviate certain nutritional shortcomings. This can subsequently help in the introduction of specific probiotics with beneficial effects.
Journal of the Science of Food and Agriculture, 2018
The focus on investigations of probiotics has been on their health beneficial roles thus far, wit... more The focus on investigations of probiotics has been on their health beneficial roles thus far, with some of the findings finally reaching food and pharmaceutical industries to commercialize their products. In biocontrol research some microbes mainly isolated from plants have shown antagonism towards both enteric and plant pathogens and out of them, some represent probiotic species. Fresh fruits and vegetables are upheld as health promoting dietary components, and if probiotics could be used to control pathogens on them, they could turn out to be even more healthy. The fresh produce industry still depends on agrochemicals and the upward trend in the demand for highly priced organically grown produce indicates consumer concern of agrochemical usage. If the potential of probiotic organisms to serve as biocontrol agents on fresh produce is exploited, all fresh produce can be made as safe as organically grown produce, and elevate them to be much more wholesome. This review appraises feasibility for such a move by evaluating how research has progressed in both disciplines (probiotic and biocontrol) and suggests sharing results from research via information technology,
Ceylon Journal of Science, 2019
Microgreens which are tender immature seedlings of vegetables and herbs are known for their healt... more Microgreens which are tender immature seedlings of vegetables and herbs are known for their health beneficial effects. The concept of microgreens is generally less popular in many countries including Sri Lanka. Ten species were tested to obtain data on seed germination, height gain, leaf area expansion, and consumer acceptance. Of these, three species of which the seeds are commonly consumed in Sri Lanka were analyzed for antioxidant activities as seeds, sprouts, and microgreens. Seed germination of most of the species was>75% with the time taken to reach 75% germination (G 75) varying from 1 to >14 days. A strong positive correlation between seedling and leaf area was observed (R 2 =0.8). Lettuce and carrot were found to be the most preferred microgreens followed by green peas, red amaranth and finger millet. For the three selected species where respective seeds, sprouts, and microgreens were compared, higher antioxidant activities were recorded in finger millet seeds and sesame microgreens; IC 50 697 µg/mL and IC 50 772 µg/mL respectively with the latter recording a high total phenol content (4873 mg/100g dry weight). Green pea microgreens showed higher total phenol content than its seeds and sprouts (1871 mg/100 g dry weight). The information generated will be of value to introduce microgreens to countries where consumers are unfamiliar with this product.
Journal of Food Protection, 1990
The relationship between initial spore load of an aflatoxigenic mold and subsequent growth and af... more The relationship between initial spore load of an aflatoxigenic mold and subsequent growth and aflatoxin production were studied at 28 and 35°C. The initial spore loads ranges <101 to 107 spores/ml. As the spore level increased, visible growth appeared sooner and was more extensive. Growth, determined by viable plate counts, indicated that maximum growth in all the treatments reached 109 CFU/g, irrespective of the initial spore load. Mycelial growth and sporulation occurred faster at 35°C at all spore levels than at 28°C. At 28°C, unusually high amounts of aflatoxin Bl (380 ug/g) were produced when 103 spores were inoculated into 50 g rice, while the lower and the higher spore levels produced comparatively lower levels of aflatoxin. At 35°C the lowest spore level (<101 spores) produced the highest amount of aflatoxin B1 (62 μg/g). The higher spore levels at 35°C either did not result in any aflatoxin formation, or the amounts produced were negligible. At 35°C many fluorescing ...
Journal of Food Protection, 1990
The effect of three individual species of lactobacilli (Lactobacillus acidophilus, L. bulgaricus,... more The effect of three individual species of lactobacilli (Lactobacillus acidophilus, L. bulgaricus, and L. plantarum) and a commercial silage inoculant, containing three different strains of the same species, on growth and aflatoxin production of A. flavus subsp. parasiticus NRRL 2999 was determined. The study was done in three substrates; a liquid semi-synthetic broth, rice, and corn. The effect of the growing cell masses of the lactobacilli as well as the effect of metabolic products contained in cell free filtrates were determined in the liquid medium. The cells were effective in preventing growth of the mold, and bacterial metabolites were effective in reducing the amount of aflatoxin produced, although growth was not affected. The prevention of growth that was observed was determined to be relative to a pH effect and microbial competition; however, the lower levels of aflatoxin obtained in the presence of cell free supernatant culture fluids could not be explained on the basis of...
The Journal of Horticultural Science and Biotechnology, 2001
Summary When the effects of pressure infiltrated (1.03 X 105 Pa, for 2 min) dilute acetic acid on... more Summary When the effects of pressure infiltrated (1.03 X 105 Pa, for 2 min) dilute acetic acid on the shelf-life of banana (Musa AAB ‘Embul’) were examined, a 0.2% acetic acid (pH 3) treatment showed a significantly low disease score. Of other acids at pH 3 (0.05% citric acid or 0.1% ascorbic acid), tested separately, citric acid significantly reduced disease incidence. A 0.12% benomyl (as ‘Benlate’) dip was the most effective. A three-factor combination of citric acid, acetic acid and `Benlate’, all at half strength showed the lowest disease score. The results indicate that ‘Benlate’ application could be reduced by half when applied concurrently with both citric acid and acetic acid. Firmness was higher in bananas treated with any one of the three acids and the effect was significant using citric acid and acetic acid. Ethylene ripening did not negate this firmness increase. Peel pH was only slightly lower in the acid treated bananas. Anthracnose lesions caused by Colletotrichum musae inoculated into fruits 24.h after treatment, were fewer when given the three-factor combination described above, indicating that postharvest acid treatment may increase fruit resistance to anthracnose, and the direct effect of acids on the pathogen is not the main cause of reducing disease. The acetic acid treatment slightly but consistantly delayed peel colour development in all experiments.
The Journal of Horticultural Science and Biotechnology, 2004
ABSTRACT Two local isolates of the biocontrol agents Flavobacterium sp. [W5481 (a)] and Pantoea a... more ABSTRACT Two local isolates of the biocontrol agents Flavobacterium sp. [W5481 (a)] and Pantoea agglomerans (W5482) were tested on 'Embul' (Musa, AAB) banana, to determine their effects on crown rot pathogens [Colletotrichum musaeand Botryodiplodia theobromae (Lasiodiplodia theobromae)]. Viable cell preparations reduced crown rot on banana hands, with live cells in distilled water more effective than those in spent culture media. Thin layer chromatography-bioassays showed that the antibiotics of Flavobacterium sp. were more potent than those of P. agglomerans, with Rf values from inhibited areas on the plates varying with the test fungus (C. musae, B. theobromae and Cladosporium cladosporioides). Autoclaving partially reduced the activity of cell-free culture medium (CFCM) on pathogen growth. Rot development on peel disks was suppressed by live cells, but not by CFCM. There were no rots with thiabendazole. In spite of the differences in antibiotic production by the antagonists, live cells of P. agglomerans suppressed crown rot to the greatest extent. Antibiosis did not completely explain the antagonism of the bacteria. Bioformulations reduced crown rot development, and were stable after at least 6 months of storage. Although not as effective as thiabendazole, the two local isolates have some potential for the biocontrol of banana pathogens.
Thesis (M.S.)--University of Nebraska--Lincoln, 1989. Includes bibliographical references.
Journal of the National Science Foundation of Sri Lanka, 2011
Abstmct: Colletolrichuh~. gloeosporioides in difyerent parts of a single avocado tree, and its de... more Abstmct: Colletolrichuh~. gloeosporioides in difyerent parts of a single avocado tree, and its dehl-is under the tree, was enumerated a t monthly inte~lrals, during a period of two years. A positive cor~.elation between quiescent infections-QI on flowers and rainfall (RF), and a negative correlation of QI on twigs and RF were observed. The positive correlation hetween RF and QI on leaves was signiiicant only when RF was pre-lagged hy 3 months, and the level of significance increased progressively when RF was pre-lagged upto 6 months. Disease symptoms were never ohsellred on the vegetative parts ofthe tree and flowers, but a high numher of QI was observed on twigs and leaves. This is probably how C. gloeosporioides survives hetween fiviting seasons. Tllc different 1.elationships between QI on each part of the tree and RF, demonstrate how this pathogen may have adopted itself to survive on t h e tree. Thcreforc thc results suggest that onw the C. gloeosporioicles pl-opagules find their way t o a tree, t h e pathogen remains there throughout i t s life time causing anthracnose on fruits. There was a significant drop in t h e density of QI of C. glomsl~orioides on larger, mature f i i t s compwed to that of smaller, immatwe fruits. Tluoughout t h i s study, the free-living viable fungal propagule counts of dehl-is under the tree val-ied from 1 0 ' to 103 CW/g wllile those of washings of leaves, twigs and flowers varied fieom 0 to 10" CFUIg.
Journal of the National Science Foundation of Sri Lanka, 2011
The physicochemical characteristics, peel thiclcness, firmness, peel to pulp ralio, pI-I, % titra... more The physicochemical characteristics, peel thiclcness, firmness, peel to pulp ralio, pI-I, % titratable acidity (%TA), and solublc solids content (SSC), werc determined in six local cultivars of banana; 'Ambon', 'Ernbul', 'Kolilruttu', 'Seeniltehel', 'Puwalu', and 'Anamalu'. Physicochemical characteristics were comparable to those of some commercially important cultivars in other countries. A tendancy for a positive correlation (pS0.1) was observed between pairs of physical parameters (peel thickness, firmness ancl pee1:pulp). The lowest and the highest peel thiclrnesses were observed in 'Kolilcuttu' (1.27 mm) and 'Anamalu' (2.73 m m) respectively. These cultivars also recorded the lowest ('Koli.lruttu'-0.91 kgcm'2) and tha highest ('Anamalu'-2.01 kg cm.3 firmness values. The highest peel to pulp ratio was in 'Anamalu' (0.24) and the lowest, in 'Kolilcuttu' (0.09). A significantly lower pII (3.73) ancl higher %TA (10.56) were observed in 'Emlnul'. The pulp of ripe 'Seenikehel' had a significantly higher SSC (25.58Rrix). A taste preference stucly showed that 'Kolilruttu' was the most popular, while 'Ernbul' and 'Ambon' werc preferred second, equally. The least prefkrred were 'Anamalu', 'Seenilcehel' and 'Puwalu'. Initiation of anthracnose was delayed the most, in'Pi~walu', when conidia of C. n.itLsac., from typical anthracnose lesions from 'Anamalu' fruits were inoculated onto ripe fruits of the other 5 cultivars. In 'Puwalu', anthracnose development and spreading of lesions were also comparatively slow. Anlhracnose development was most rapid in 'Kolilcuttu', which also recorded the lowest firmncss and the lowest peel to pulp ratio. The correlation between lesion diameters ancl each physical parameter was negative without statistical significance.
Ceylon Journal of Science, 2022
Sri Lankan Journal of Infectious Diseases, 2021
Postharvest Pathology of Fresh Horticultural Produce, 2019
Bacteria in Agrobiology: Crop Ecosystems, 2011
... interest in biological control of soilborne pathogens, with research into biological control ... more ... interest in biological control of soilborne pathogens, with research into biological control ... the two disciplines is not surprising considering the species mentioned as PGPR and as ... studies, under controlled conditions incorporating the complex inter-actions between host, pathogen ...
Ceylon Journal of Science, 2018
The Sri Lankan diet of which the staple is rice, has unacceptable levels of antinutritional subst... more The Sri Lankan diet of which the staple is rice, has unacceptable levels of antinutritional substances, particularly phytic acid, which is associated with fibre, a dietary component originating from plant sources of food. Low anthropometric indicators among preschool children suggestive of undernutrition have remained static over several years. Some microbes that ferment food are known to produce phytase that metabolize phytic acid in addition to providing other benefits. Some of these microbes in fermented foods serve as probiotics, which help maintain homeostasis within the gut microbiota, thus providing a wide range of health benefits. At present, it is a worldwide trend to incorporate probiotics to the daily diet in fermented foods, while a market for novel probiotic foods is catching on. In the gut, probiotics can thrive on indigestible carbohydrates (fibre) serving as prebiotics. Therefore, designing synbiotic foods having both probiotics and prebiotics with enhanced benefits is also becoming popular globally. This review evaluates the feasibility of introducing a wide range of fermented foods to the Sri Lankan diet. Such a move is envisaged to diversify the local diet thus helping to alleviate certain nutritional shortcomings. This can subsequently help in the introduction of specific probiotics with beneficial effects.
Journal of the Science of Food and Agriculture, 2018
The focus on investigations of probiotics has been on their health beneficial roles thus far, wit... more The focus on investigations of probiotics has been on their health beneficial roles thus far, with some of the findings finally reaching food and pharmaceutical industries to commercialize their products. In biocontrol research some microbes mainly isolated from plants have shown antagonism towards both enteric and plant pathogens and out of them, some represent probiotic species. Fresh fruits and vegetables are upheld as health promoting dietary components, and if probiotics could be used to control pathogens on them, they could turn out to be even more healthy. The fresh produce industry still depends on agrochemicals and the upward trend in the demand for highly priced organically grown produce indicates consumer concern of agrochemical usage. If the potential of probiotic organisms to serve as biocontrol agents on fresh produce is exploited, all fresh produce can be made as safe as organically grown produce, and elevate them to be much more wholesome. This review appraises feasibility for such a move by evaluating how research has progressed in both disciplines (probiotic and biocontrol) and suggests sharing results from research via information technology,
Ceylon Journal of Science, 2019
Microgreens which are tender immature seedlings of vegetables and herbs are known for their healt... more Microgreens which are tender immature seedlings of vegetables and herbs are known for their health beneficial effects. The concept of microgreens is generally less popular in many countries including Sri Lanka. Ten species were tested to obtain data on seed germination, height gain, leaf area expansion, and consumer acceptance. Of these, three species of which the seeds are commonly consumed in Sri Lanka were analyzed for antioxidant activities as seeds, sprouts, and microgreens. Seed germination of most of the species was>75% with the time taken to reach 75% germination (G 75) varying from 1 to >14 days. A strong positive correlation between seedling and leaf area was observed (R 2 =0.8). Lettuce and carrot were found to be the most preferred microgreens followed by green peas, red amaranth and finger millet. For the three selected species where respective seeds, sprouts, and microgreens were compared, higher antioxidant activities were recorded in finger millet seeds and sesame microgreens; IC 50 697 µg/mL and IC 50 772 µg/mL respectively with the latter recording a high total phenol content (4873 mg/100g dry weight). Green pea microgreens showed higher total phenol content than its seeds and sprouts (1871 mg/100 g dry weight). The information generated will be of value to introduce microgreens to countries where consumers are unfamiliar with this product.
Journal of Food Protection, 1990
The relationship between initial spore load of an aflatoxigenic mold and subsequent growth and af... more The relationship between initial spore load of an aflatoxigenic mold and subsequent growth and aflatoxin production were studied at 28 and 35°C. The initial spore loads ranges <101 to 107 spores/ml. As the spore level increased, visible growth appeared sooner and was more extensive. Growth, determined by viable plate counts, indicated that maximum growth in all the treatments reached 109 CFU/g, irrespective of the initial spore load. Mycelial growth and sporulation occurred faster at 35°C at all spore levels than at 28°C. At 28°C, unusually high amounts of aflatoxin Bl (380 ug/g) were produced when 103 spores were inoculated into 50 g rice, while the lower and the higher spore levels produced comparatively lower levels of aflatoxin. At 35°C the lowest spore level (<101 spores) produced the highest amount of aflatoxin B1 (62 μg/g). The higher spore levels at 35°C either did not result in any aflatoxin formation, or the amounts produced were negligible. At 35°C many fluorescing ...
Journal of Food Protection, 1990
The effect of three individual species of lactobacilli (Lactobacillus acidophilus, L. bulgaricus,... more The effect of three individual species of lactobacilli (Lactobacillus acidophilus, L. bulgaricus, and L. plantarum) and a commercial silage inoculant, containing three different strains of the same species, on growth and aflatoxin production of A. flavus subsp. parasiticus NRRL 2999 was determined. The study was done in three substrates; a liquid semi-synthetic broth, rice, and corn. The effect of the growing cell masses of the lactobacilli as well as the effect of metabolic products contained in cell free filtrates were determined in the liquid medium. The cells were effective in preventing growth of the mold, and bacterial metabolites were effective in reducing the amount of aflatoxin produced, although growth was not affected. The prevention of growth that was observed was determined to be relative to a pH effect and microbial competition; however, the lower levels of aflatoxin obtained in the presence of cell free supernatant culture fluids could not be explained on the basis of...
The Journal of Horticultural Science and Biotechnology, 2001
Summary When the effects of pressure infiltrated (1.03 X 105 Pa, for 2 min) dilute acetic acid on... more Summary When the effects of pressure infiltrated (1.03 X 105 Pa, for 2 min) dilute acetic acid on the shelf-life of banana (Musa AAB ‘Embul’) were examined, a 0.2% acetic acid (pH 3) treatment showed a significantly low disease score. Of other acids at pH 3 (0.05% citric acid or 0.1% ascorbic acid), tested separately, citric acid significantly reduced disease incidence. A 0.12% benomyl (as ‘Benlate’) dip was the most effective. A three-factor combination of citric acid, acetic acid and `Benlate’, all at half strength showed the lowest disease score. The results indicate that ‘Benlate’ application could be reduced by half when applied concurrently with both citric acid and acetic acid. Firmness was higher in bananas treated with any one of the three acids and the effect was significant using citric acid and acetic acid. Ethylene ripening did not negate this firmness increase. Peel pH was only slightly lower in the acid treated bananas. Anthracnose lesions caused by Colletotrichum musae inoculated into fruits 24.h after treatment, were fewer when given the three-factor combination described above, indicating that postharvest acid treatment may increase fruit resistance to anthracnose, and the direct effect of acids on the pathogen is not the main cause of reducing disease. The acetic acid treatment slightly but consistantly delayed peel colour development in all experiments.
The Journal of Horticultural Science and Biotechnology, 2004
ABSTRACT Two local isolates of the biocontrol agents Flavobacterium sp. [W5481 (a)] and Pantoea a... more ABSTRACT Two local isolates of the biocontrol agents Flavobacterium sp. [W5481 (a)] and Pantoea agglomerans (W5482) were tested on 'Embul' (Musa, AAB) banana, to determine their effects on crown rot pathogens [Colletotrichum musaeand Botryodiplodia theobromae (Lasiodiplodia theobromae)]. Viable cell preparations reduced crown rot on banana hands, with live cells in distilled water more effective than those in spent culture media. Thin layer chromatography-bioassays showed that the antibiotics of Flavobacterium sp. were more potent than those of P. agglomerans, with Rf values from inhibited areas on the plates varying with the test fungus (C. musae, B. theobromae and Cladosporium cladosporioides). Autoclaving partially reduced the activity of cell-free culture medium (CFCM) on pathogen growth. Rot development on peel disks was suppressed by live cells, but not by CFCM. There were no rots with thiabendazole. In spite of the differences in antibiotic production by the antagonists, live cells of P. agglomerans suppressed crown rot to the greatest extent. Antibiosis did not completely explain the antagonism of the bacteria. Bioformulations reduced crown rot development, and were stable after at least 6 months of storage. Although not as effective as thiabendazole, the two local isolates have some potential for the biocontrol of banana pathogens.
Thesis (M.S.)--University of Nebraska--Lincoln, 1989. Includes bibliographical references.
Journal of the National Science Foundation of Sri Lanka, 2011
Abstmct: Colletolrichuh~. gloeosporioides in difyerent parts of a single avocado tree, and its de... more Abstmct: Colletolrichuh~. gloeosporioides in difyerent parts of a single avocado tree, and its dehl-is under the tree, was enumerated a t monthly inte~lrals, during a period of two years. A positive cor~.elation between quiescent infections-QI on flowers and rainfall (RF), and a negative correlation of QI on twigs and RF were observed. The positive correlation hetween RF and QI on leaves was signiiicant only when RF was pre-lagged hy 3 months, and the level of significance increased progressively when RF was pre-lagged upto 6 months. Disease symptoms were never ohsellred on the vegetative parts ofthe tree and flowers, but a high numher of QI was observed on twigs and leaves. This is probably how C. gloeosporioides survives hetween fiviting seasons. Tllc different 1.elationships between QI on each part of the tree and RF, demonstrate how this pathogen may have adopted itself to survive on t h e tree. Thcreforc thc results suggest that onw the C. gloeosporioicles pl-opagules find their way t o a tree, t h e pathogen remains there throughout i t s life time causing anthracnose on fruits. There was a significant drop in t h e density of QI of C. glomsl~orioides on larger, mature f i i t s compwed to that of smaller, immatwe fruits. Tluoughout t h i s study, the free-living viable fungal propagule counts of dehl-is under the tree val-ied from 1 0 ' to 103 CW/g wllile those of washings of leaves, twigs and flowers varied fieom 0 to 10" CFUIg.
Journal of the National Science Foundation of Sri Lanka, 2011
The physicochemical characteristics, peel thiclcness, firmness, peel to pulp ralio, pI-I, % titra... more The physicochemical characteristics, peel thiclcness, firmness, peel to pulp ralio, pI-I, % titratable acidity (%TA), and solublc solids content (SSC), werc determined in six local cultivars of banana; 'Ambon', 'Ernbul', 'Kolilruttu', 'Seeniltehel', 'Puwalu', and 'Anamalu'. Physicochemical characteristics were comparable to those of some commercially important cultivars in other countries. A tendancy for a positive correlation (pS0.1) was observed between pairs of physical parameters (peel thickness, firmness ancl pee1:pulp). The lowest and the highest peel thiclrnesses were observed in 'Kolilcuttu' (1.27 mm) and 'Anamalu' (2.73 m m) respectively. These cultivars also recorded the lowest ('Koli.lruttu'-0.91 kgcm'2) and tha highest ('Anamalu'-2.01 kg cm.3 firmness values. The highest peel to pulp ratio was in 'Anamalu' (0.24) and the lowest, in 'Kolilcuttu' (0.09). A significantly lower pII (3.73) ancl higher %TA (10.56) were observed in 'Emlnul'. The pulp of ripe 'Seenikehel' had a significantly higher SSC (25.58Rrix). A taste preference stucly showed that 'Kolilruttu' was the most popular, while 'Ernbul' and 'Ambon' werc preferred second, equally. The least prefkrred were 'Anamalu', 'Seenilcehel' and 'Puwalu'. Initiation of anthracnose was delayed the most, in'Pi~walu', when conidia of C. n.itLsac., from typical anthracnose lesions from 'Anamalu' fruits were inoculated onto ripe fruits of the other 5 cultivars. In 'Puwalu', anthracnose development and spreading of lesions were also comparatively slow. Anlhracnose development was most rapid in 'Kolilcuttu', which also recorded the lowest firmncss and the lowest peel to pulp ratio. The correlation between lesion diameters ancl each physical parameter was negative without statistical significance.